Why Grolar Bear Numbers Increase With Climate Change

The grolar bear, also known as the pizzly bear, is the product of a mating between a polar bear and a grizzly bear. This crossbreeding occurs when the habitats of polar and grizzly bears overlap, usually due to polar bears being pushed southward as sea ice melts, bringing them into contact with grizzlies.

According to a 2024 study, all known wild grolar bears (only eight of which have been confirmed to date) descend from a single female polar bear and multiple male grizzly bears.

The first confirmed grolar bear was identified in 2006 in the Canadian Arctic when Jim Martell, an Idaho hunter, unknowingly shot what appeared to be a polar bear — but it had physical traits of both species.

The hybrid nature of the grolar bear highlights how two species that have diverged over thousands of years can still interbreed. For example, the liger — a cross between a lion and a tiger — demonstrates a similar phenomenon, combining physical and behavioral traits of both species despite their evolutionary separation and distinct habitats.

Polar bears evolved to thrive in the icy expanses of the Arctic, where they hunt seals and rely on the frozen landscape. On the other hand, grizzly bears — a subspecies of brown bears — inhabit forests, mountains and plains, relying on a varied diet.

When these two species mate, their offspring inherit traits from both parents, creating a grizzly polar bear hybrid that should theoretically be suited to both environments. But that may not be the case.

Dr. Evan Richardson, a polar bear research scientist, suggests that grolar or pizzly bears are unlikely to be better adapted to the changing Arctic environment. According to Richardson, these hybrids may not be well-suited for life on either land or sea, making them less effective as polar or brown bears.

He notes that, while hybridization has occurred in the past, hybrids generally don't persist over the long term, suggesting that such mixed traits offer limited adaptability.

Grolar bears have a blend of physical features from both polar and grizzly bears. They tend to be smaller than pure polar bears but larger than typical grizzlies. Their fur is usually a light brown or off-white color, giving them a creamy appearance that combines the polar bear's white fur and the grizzly bear's darker coat.

These hybrid bears also inherit long, powerful claws from their grizzly bear parent, perfect for digging and foraging, while also retaining the large, broad paws of a polar bear, which are suited for walking on ice.

A key difference between grolar bears and their polar or grizzly parents is the shape of their heads. Polar bears have longer, narrower skulls adapted for hunting seals, while grizzly bears have wider, rounder heads for crushing plants and prey.

Grolar bears typically display a blend of these skull shapes, giving them a unique profile. They are also stockier than polar bears but not as bulky as grizzlies, making them well-suited for land and icy environments.

These distinct types of bears have unique adaptations, habitats and behaviors. Polar bears, the largest of the three, are native to the Arctic and are well-adapted for life on ice with their thick, water-repellent fur and large, slightly webbed paws, which help them swim and navigate icy waters. Their diet mainly consists of seals, making them a top predator in their icy habitat.

Grizzly bears, on the other hand, are found primarily in North America. Known for their muscular shoulders and long claws, they are adept at digging and foraging, often feeding on roots, berries and fish. Unlike polar bears, they prefer forested or mountainous regions and hibernate during the winter.

Grolar bears have features from both parents — such as intermediate fur color and physical characteristics. They're usually found in regions where polar and grizzly habitats overlap, likely due to changing climates. Grolars can exhibit a mix of polar and grizzly traits, creating a unique blend of behaviors and dietary habits that reflect their dual heritage.

The life cycle of grolar bears appears to mirror that of their parent species. Cubs stay with their mother for about two to three years, learning essential survival skills, including hunting, foraging and navigating their surroundings.

Scientists have limited data on how upbringing might vary depending on the mother's species. However, a cub raised by a polar bear might learn ice-adapted hunting techniques, while one raised by a grizzly mother might adapt to more terrestrial foraging.

Though scarce, grolar bears can mate with polar bears or grizzlies, potentially creating offspring with a blend of traits. This genetic blending, observed through DNA studies, could result in hybrids that resemble one parent more than the other over generations.

In the wild, the lifespan of grolar bears is estimated to be around 20 to 30 years, similar to that of their parent species. However, since grolar bears are a recent and rare discovery, with only a few documented individuals, this estimate is based on the known lifespans of polar bears and grizzly bears rather than direct observation.

The big question surrounding grolar bears is whether they can survive and thrive in the wild. These hybrid bears are a product of a rapidly changing environment, where polar bears are being forced out of their traditional sea ice habitats and into areas populated by grizzlies.

While polar bears evolved to rely on the frozen Arctic for hunting seals, the hybrid nature of grolar bears may give them a survival advantage in a warming world, where they can forage on land like their grizzly bear parent.

However, grolar bears also face unique challenges. They are not as specialized as either parent species; polar bears are expert hunters of seals, and grizzlies have perfected foraging and hunting on land. As such, grolar bears must adapt to a variety of food sources and environments to survive.

So far, the polar bear-grizzly hybrids have been seen foraging for food on land, including vegetation and small mammals, suggesting that they might inherit the grizzly's more adaptable diet.

The long-term viability of grolar bears in the wild is still unknown. As climate change continues to reshape the Arctic and the habitats of polar and grizzly bears overlap even more, these hybrid bears could become more common.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.